There is no liability if it's not your main source of income, even then it's pretty hard for them to get you.
Many years ago they took a person to court who was self employed and his business lost money every year, but he made huge profits gambling.
Without going into the ins and outs the Judges decision was that if he decided in favour of the taxation office then that meant that anyone could claim gambling losses against their income as the taxation office couldn't have it both ways. The taxation office did their sums ******** themselves and withdrew the action.
I am still very wary of the **************s so have put some money in a friends business which I actually make a profit from and that is my taxable income.
Last year I got $9000+ back with my family allowance ( which I claim yearly ) and never paid that much in tax.
All perfectly legal and suits me fine.